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* Modify error context callback functions to not assume that they can fetchTom Lane2010-03-19
| | | | | | | | | | | | | | | | | | catalog entries via SearchSysCache and related operations. Although, at the time that these callbacks are called by elog.c, we have not officially aborted the current transaction, it still seems rather risky to initiate any new catalog fetches. In all these cases the needed information is readily available in the caller and so it's just a matter of a bit of extra notation to pass it to the callback. Per crash report from Dennis Koegel. I've concluded that the real fix for his problem is to clear the error context stack at entry to proc_exit, but it still seems like a good idea to make the callbacks a bit less fragile for other cases. Backpatch to 8.4. We could go further back, but the patch doesn't apply cleanly. In the absence of proof that this fixes something and isn't just paranoia, I'm not going to expend the effort.
* pgindent run for 9.0Bruce Momjian2010-02-26
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* Clean up handling of XactReadOnly and RecoveryInProgress checks.Tom Lane2010-02-20
| | | | | | | | | | | | | | | | | | Add some checks that seem logically necessary, in particular let's make real sure that HS slave sessions cannot create temp tables. (If they did they would think that temp tables belonging to the master's session with the same BackendId were theirs. We *must* not allow myTempNamespace to become set in a slave session.) Change setval() and nextval() so that they are only allowed on temp sequences in a read-only transaction. This seems consistent with what we allow for table modifications in read-only transactions. Since an HS slave can't have a temp sequence, this also provides a nicer cure for the setval PANIC reported by Erik Rijkers. Make the error messages more uniform, and have them mention the specific command being complained of. This seems worth the trifling amount of extra code, since people are likely to see such messages a lot more than before.
* Fix ExecEvalArrayRef to pass down the old value of the array element or sliceTom Lane2010-02-18
| | | | | | | | | | | | | being assigned to, in case the expression to be assigned is a FieldStore that would need to modify that value. The need for this was foreseen some time ago, but not implemented then because we did not have arrays of composites. Now we do, but the point evidently got overlooked in that patch. Net result is that updating a field of an array element doesn't work right, as illustrated if you try the new regression test on an unpatched backend. Noted while experimenting with EXPLAIN VERBOSE, which has also got some issues in this area. Backpatch to 8.3, where arrays of composites were introduced.
* Wrap calls to SearchSysCache and related functions using macros.Robert Haas2010-02-14
| | | | | | | | | | | | The purpose of this change is to eliminate the need for every caller of SearchSysCache, SearchSysCacheCopy, SearchSysCacheExists, GetSysCacheOid, and SearchSysCacheList to know the maximum number of allowable keys for a syscache entry (currently 4). This will make it far easier to increase the maximum number of keys in a future release should we choose to do so, and it makes the code shorter, too. Design and review by Tom Lane.
* Extend the set of frame options supported for window functions.Tom Lane2010-02-12
| | | | | | | | | This patch allows the frame to start from CURRENT ROW (in either RANGE or ROWS mode), and it also adds support for ROWS n PRECEDING and ROWS n FOLLOWING start and end points. (RANGE value PRECEDING/FOLLOWING isn't there yet --- the grammar works, but that's all.) Hitoshi Harada, reviewed by Pavel Stehule
* Fix up rickety handling of relation-truncation interlocks.Tom Lane2010-02-09
| | | | | | | | | | | | | | | | | | | | Move rd_targblock, rd_fsm_nblocks, and rd_vm_nblocks from relcache to the smgr relation entries, so that they will get reset to InvalidBlockNumber whenever an smgr-level flush happens. Because we now send smgr invalidation messages immediately (not at end of transaction) when a relation truncation occurs, this ensures that other backends will reset their values before they next access the relation. We no longer need the unreliable assumption that a VACUUM that's doing a truncation will hold its AccessExclusive lock until commit --- in fact, we can intentionally release that lock as soon as we've completed the truncation. This patch therefore reverts (most of) Alvaro's patch of 2009-11-10, as well as my marginal hacking on it yesterday. We can also get rid of assorted no-longer-needed relcache flushes, which are far more expensive than an smgr flush because they kill a lot more state. In passing this patch fixes smgr_redo's failure to perform visibility-map truncation, and cleans up some rather dubious assumptions in freespace.c and visibilitymap.c about when rd_fsm_nblocks and rd_vm_nblocks can be out of date.
* Create an official API function for C functions to use to check if they areTom Lane2010-02-08
| | | | | | | | | | being called as aggregates, and to get the aggregate transition state memory context if needed. Use it instead of poking directly into AggState and WindowAggState in places that shouldn't know so much. We should have done this in 8.4, probably, but better late than never. Revised version of a patch by Hitoshi Harada.
* Remove old-style VACUUM FULL (which was known for a little while asTom Lane2010-02-08
| | | | | | | | | | | | | | | | | VACUUM FULL INPLACE), along with a boatload of subsidiary code and complexity. Per discussion, the use case for this method of vacuuming is no longer large enough to justify maintaining it; not to mention that we don't wish to invest the work that would be needed to make it play nicely with Hot Standby. Aside from the code directly related to old-style VACUUM FULL, this commit removes support for certain WAL record types that could only be generated within VACUUM FULL, redirect-pointer removal in heap_page_prune, and nontransactional generation of cache invalidation sinval messages (the last being the sticking point for Hot Standby). We still have to retain all code that copes with finding HEAP_MOVED_OFF and HEAP_MOVED_IN flag bits on existing tuples. This can't be removed as long as we want to support in-place update from pre-9.0 databases.
* Create a "relation mapping" infrastructure to support changing the relfilenodesTom Lane2010-02-07
| | | | | | | | | | | | | | | | | | | | | | | of shared or nailed system catalogs. This has two key benefits: * The new CLUSTER-based VACUUM FULL can be applied safely to all catalogs. * We no longer have to use an unsafe reindex-in-place approach for reindexing shared catalogs. CLUSTER on nailed catalogs now works too, although I left it disabled on shared catalogs because the resulting pg_index.indisclustered update would only be visible in one database. Since reindexing shared system catalogs is now fully transactional and crash-safe, the former special cases in REINDEX behavior have been removed; shared catalogs are treated the same as non-shared. This commit does not do anything about the recently-discussed problem of deadlocks between VACUUM FULL/CLUSTER on a system catalog and other concurrent queries; will address that in a separate patch. As a stopgap, parallel_schedule has been tweaked to run vacuum.sql by itself, to avoid such failures during the regression tests.
* Move the responsibility of writing a "unlogged WAL operation" record fromHeikki Linnakangas2010-02-03
| | | | | | heap_sync() to the callers, because heap_sync() is sometimes called even if the operation itself is WAL-logged. This eliminates the bogus unlogged records from CLUSTER that Simon Riggs reported, patch by Fujii Masao.
* Augment EXPLAIN output with more details on Hash nodes.Robert Haas2010-02-01
| | | | | | We show the number of buckets, the number of batches (and also the original number if it has changed), and the peak space used by the hash table. Minor executor changes to track peak space used.
* Fix memory leak created by deferrable-index-constraints patches.Tom Lane2010-01-31
| | | | | | | | | We need to free the OID list returned by ExecInsertIndexTuples to avoid a query-lifespan memory leak. When many rows require rechecking, this can be a significant leak --- it's even more than the space used for the queued trigger events. Dean Rasheed
* Type table featurePeter Eisentraut2010-01-28
| | | | This adds the CREATE TABLE name OF type command, per SQL standard.
* Introduce Streaming Replication.Heikki Linnakangas2010-01-15
| | | | | | | | | | | | | | | | | | | | This includes two new kinds of postmaster processes, walsenders and walreceiver. Walreceiver is responsible for connecting to the primary server and streaming WAL to disk, while walsender runs in the primary server and streams WAL from disk to the client. Documentation still needs work, but the basics are there. We will probably pull the replication section to a new chapter later on, as well as the sections describing file-based replication. But let's do that as a separate patch, so that it's easier to see what has been added/changed. This patch also adds a new section to the chapter about FE/BE protocol, documenting the protocol used by walsender/walreceivxer. Bump catalog version because of two new functions, pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for monitoring the progress of replication. Fujii Masao, with additional hacking by me
* Improve ExecEvalVar's handling of whole-row variables in cases where theTom Lane2010-01-11
| | | | | | | | | | | | | | | | | rowtype contains dropped columns. Sometimes the input tuple will be formed from a select targetlist in which dropped columns are filled with a NULL of an arbitrary type (the planner typically uses INT4, since it can't tell what type the dropped column really was). So we need to relax the rowtype compatibility check to not insist on physical compatibility if the actual column value is NULL. In principle we might need to do this for functions returning composite types, too (see tupledesc_match()). In practice there doesn't seem to be a bug there, probably because the function will be using the same cached rowtype descriptor as the caller. Fixing that code path would require significant rearrangement, so I left it alone for now. Per complaint from Filip Rembialkowski.
* Make ExecEvalFieldSelect throw a more intelligible error if it's asked toTom Lane2010-01-09
| | | | | | | | extract a system column, and remove a couple of lines that are useless in light of the fact that we aren't ever going to support this case. There isn't much point in trying to make this work because a tuple Datum does not carry many of the system columns. Per experimentation with a case reported by Dean Rasheed; we'll have to fix his problem somewhere else.
* Fix oversight in EvalPlanQualFetch: after failing to lock a tuple becauseTom Lane2010-01-08
| | | | | | | | | | | | | | | | someone else has just updated it, we have to set priorXmax to that tuple's xmax (ie, the XID of the other xact that updated it) before looping back to examine the next tuple. Obviously, the next tuple in the update chain should have that XID as its xmin, not the same xmin as the preceding tuple that we had been trying to lock. The mismatch would cause the EvalPlanQual logic to decide that the tuple chain ended in a deletion, when actually there was a live tuple that should have been found. I inserted this error when recently adding logic to EvalPlanQual to make it lock tuples before returning them (as opposed to the old method in which the lock would occur much later, causing a great deal of work to be wasted if we only then discover someone else updated it). Sigh. Per today's report from Takahiro Itagaki of inconsistent results during pgbench runs.
* Preserve relfilenodes:Bruce Momjian2010-01-06
| | | | | Add support to pg_dump --binary-upgrade to preserve all relfilenodes, for use by pg_migrator.
* Add support for doing FULL JOIN ON FALSE. While this is really a ratherTom Lane2010-01-05
| | | | | | | | | | peculiar variant of UNION ALL, and so wouldn't likely get written directly as-is, it's possible for it to arise as a result of simplification of less-obviously-silly queries. In particular, now that we can do flattening of subqueries that have constant outputs and are underneath an outer join, it's possible for the case to result from simplification of queries of the type exhibited in bug #5263. Back-patch to 8.4 to avoid a functionality regression for this type of query.
* When estimating the selectivity of an inequality "column > constant" orTom Lane2010-01-04
| | | | | | | | | | | | | | | "column < constant", and the comparison value is in the first or last histogram bin or outside the histogram entirely, try to fetch the actual column min or max value using an index scan (if there is an index on the column). If successful, replace the lower or upper histogram bound with that value before carrying on with the estimate. This limits the estimation error caused by moving min/max values when the comparison value is close to the min or max. Per a complaint from Josh Berkus. It is tempting to consider using this mechanism for mergejoinscansel as well, but that would inject index fetches into main-line join estimation not just endpoint cases. I'm refraining from that until we can get a better handle on the costs of doing this type of lookup.
* check_exclusion_constraint didn't actually work correctly for indexTom Lane2010-01-02
| | | | | | | expressions: FormIndexDatum requires the estate's scantuple to already point at the tuple the values are supposedly being extracted from. Adjust test case so that this type of confusion will be exposed. Per report from hubert depesz lubaczewski.
* Update copyright for the year 2010.Bruce Momjian2010-01-02
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* Add an "argisrow" field to NullTest nodes, following a plan made way back inTom Lane2010-01-01
| | | | | | 8.2beta but never carried out. This avoids repetitive tests of whether the argument is of scalar or composite type. Also, be a bit more paranoid about composite arguments in some places where we previously weren't checking.
* Support "x IS NOT NULL" clauses as indexscan conditions. This turns outTom Lane2010-01-01
| | | | | | | | | | | to be just a minor extension of the previous patch that made "x IS NULL" indexable, because we can treat the IS NOT NULL condition as if it were "x < NULL" or "x > NULL" (depending on the index's NULLS FIRST/LAST option), just like IS NULL is treated like "x = NULL". Aside from any possible usefulness in its own right, this is an important improvement for index-optimized MAX/MIN aggregates: it is now reliably possible to get a column's min or max value cheaply, even when there are a lot of nulls cluttering the interesting end of the index.
* Add the ability to store inheritance-tree statistics in pg_statistic,Tom Lane2009-12-29
| | | | | | | | and teach ANALYZE to compute such stats for tables that have subclasses. Per my proposal of yesterday. autovacuum still needs to be taught about running ANALYZE on parent tables when their subclasses change, but the feature is useful even without that.
* Previous fix for temporary file management broke returning a set fromHeikki Linnakangas2009-12-29
| | | | | | | | | | | | | | PL/pgSQL function within an exception handler. Make sure we use the right resource owner when we create the tuplestore to hold returned tuples. Simplify tuplestore API so that the caller doesn't need to be in the right memory context when calling tuplestore_put* functions. tuplestore.c automatically switches to the memory context used when the tuplestore was created. Tuplesort was already modified like this earlier. This patch also removes the now useless MemoryContextSwitch calls from callers. Report by Aleksei on pgsql-bugs on Dec 22 2009. Backpatch to 8.1, like the previous patch that broke this.
* Support ORDER BY within aggregate function calls, at long last providing aTom Lane2009-12-15
| | | | | | | | | | | | | non-kluge method for controlling the order in which values are fed to an aggregate function. At the same time eliminate the old implementation restriction that DISTINCT was only supported for single-argument aggregates. Possibly release-notable behavioral change: formerly, agg(DISTINCT x) dropped null values of x unconditionally. Now, it does so only if the agg transition function is strict; otherwise nulls are treated as DISTINCT normally would, ie, you get one copy. Andrew Gierth, reviewed by Hitoshi Harada
* Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.Robert Haas2009-12-15
| | | | | | | | This patch also removes buffer-usage statistics from the track_counts output, since this (or the global server statistics) is deemed to be a better interface to this information. Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.
* Fix a bug introduced when set-returning SQL functions were made inline-able:Tom Lane2009-12-14
| | | | | | | | | | | | | | we have to cope with the possibility that the declared result rowtype contains dropped columns. This fails in 8.4, as per bug #5240. While at it, be more paranoid about inserting binary coercions when inlining. The pre-8.4 code did not really need to worry about that because it could not inline at all in any case where an added coercion could change the behavior of the function's statement. However, when inlining a SRF we allow sorting, grouping, and set-ops such as UNION. In these cases, modifying one of the targetlist entries that the sort/group/setop depends on could conceivably change the behavior of the function's statement --- so don't inline when such a case applies.
* Ensure that the result tuple of an EvalPlanQual cycle gets materializedTom Lane2009-12-11
| | | | | | | | before we zap the input tuple. Otherwise, pass-by-reference columns of the result slot are likely to contain just references to the input tuple, leading to big trouble if the pfree'd space is reused. Per trouble report from Jaime Casanova. This is a new bug in the recent rewrite of EvalPlanQual, so nothing to back-patch.
* Prevent indirect security attacks via changing session-local state withinTom Lane2009-12-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | an allegedly immutable index function. It was previously recognized that we had to prevent such a function from executing SET/RESET ROLE/SESSION AUTHORIZATION, or it could trivially obtain the privileges of the session user. However, since there is in general no privilege checking for changes of session-local state, it is also possible for such a function to change settings in a way that might subvert later operations in the same session. Examples include changing search_path to cause an unexpected function to be called, or replacing an existing prepared statement with another one that will execute a function of the attacker's choosing. The present patch secures VACUUM, ANALYZE, and CREATE INDEX/REINDEX against these threats, which are the same places previously deemed to need protection against the SET ROLE issue. GUC changes are still allowed, since there are many useful cases for that, but we prevent security problems by forcing a rollback of any GUC change after completing the operation. Other cases are handled by throwing an error if any change is attempted; these include temp table creation, closing a cursor, and creating or deleting a prepared statement. (In 7.4, the infrastructure to roll back GUC changes doesn't exist, so we settle for rejecting changes of "search_path" in these contexts.) Original report and patch by Gurjeet Singh, additional analysis by Tom Lane. Security: CVE-2009-4136
* Add exclusion constraints, which generalize the concept of uniqueness toTom Lane2009-12-07
| | | | | | | | support any indexable commutative operator, not just equality. Two rows violate the exclusion constraint if "row1.col OP row2.col" is TRUE for each of the columns in the constraint. Jeff Davis, reviewed by Robert Haas
* Add a WHEN clause to CREATE TRIGGER, allowing a boolean expression to beTom Lane2009-11-20
| | | | | | | | | | | checked to determine whether the trigger should be fired. For BEFORE triggers this is mostly a matter of spec compliance; but for AFTER triggers it can provide a noticeable performance improvement, since queuing of a deferred trigger event and re-fetching of the row(s) at end of statement can be short-circuited if the trigger does not need to be fired. Takahiro Itagaki, reviewed by KaiGai Kohei.
* Fix WHERE CURRENT OF to work as designed within plpgsql. The argumentTom Lane2009-11-09
| | | | | | | can be the name of a plpgsql cursor variable, which formerly was converted to $N before the core parser saw it, but that's no longer the case. Deal with plain name references to plpgsql variables, and add a regression test case that exposes the failure.
* Add support for invoking parser callback hooks via SPI and in cached plans.Tom Lane2009-11-04
| | | | | | | | | | | | As proof of concept, modify plpgsql to use the hooks. plpgsql is still inserting $n symbols textually, but the "back end" of the parsing process now goes through the ParamRef hook instead of using a fixed parameter-type array, and then execution only fetches actually-referenced parameters, using a hook added to ParamListInfo. Although there's a lot left to be done in plpgsql, this already cures the "if (TG_OP = 'INSERT' and NEW.foo ...)" problem, as illustrated by the changed regression test.
* Make the overflow guards in ExecChooseHashTableSize be more protective.Tom Lane2009-10-30
| | | | | | | | | | | | | | | The original coding ensured nbuckets and nbatch didn't exceed INT_MAX, which while not insane on its own terms did nothing to protect subsequent code like "palloc(nbatch * sizeof(BufFile *))". Since enormous join size estimates might well be planner error rather than reality, it seems best to constrain the initial sizes to be not more than work_mem/sizeof(pointer), thus ensuring the allocated arrays don't exceed work_mem. We will allow nbatch to get bigger than that during subsequent ExecHashIncreaseNumBatches calls, but we should still guard against integer overflow in those palloc requests. Per bug #5145 from Bernt Marius Johnsen. Although the given test case only seems to fail back to 8.2, previous releases have variants of this issue, so patch all supported branches.
* Re-implement EvalPlanQual processing to improve its performance and eliminateTom Lane2009-10-26
| | | | | | | | | | | | | | | | | | | | | | | | | a lot of strange behaviors that occurred in join cases. We now identify the "current" row for every joined relation in UPDATE, DELETE, and SELECT FOR UPDATE/SHARE queries. If an EvalPlanQual recheck is necessary, we jam the appropriate row into each scan node in the rechecking plan, forcing it to emit only that one row. The former behavior could rescan the whole of each joined relation for each recheck, which was terrible for performance, and what's much worse could result in duplicated output tuples. Also, the original implementation of EvalPlanQual could not re-use the recheck execution tree --- it had to go through a full executor init and shutdown for every row to be tested. To avoid this overhead, I've associated a special runtime Param with each LockRows or ModifyTable plan node, and arranged to make every scan node below such a node depend on that Param. Thus, by signaling a change in that Param, the EPQ machinery can just rescan the already-built test plan. This patch also adds a prohibition on set-returning functions in the targetlist of SELECT FOR UPDATE/SHARE. This is needed to avoid the duplicate-output-tuple problem. It seems fairly reasonable since the other restrictions on SELECT FOR UPDATE are meant to ensure that there is a unique correspondence between source tuples and result tuples, which an output SRF destroys as much as anything else does.
* Move the handling of SELECT FOR UPDATE locking and rechecking out ofTom Lane2009-10-12
| | | | | | | | | | | | | | | | | | | execMain.c and into a new plan node type LockRows. Like the recent change to put table updating into a ModifyTable plan node, this increases planning flexibility by allowing the operations to occur below the top level of the plan tree. It's necessary in any case to restore the previous behavior of having FOR UPDATE locking occur before ModifyTable does. This partially refactors EvalPlanQual to allow multiple rows-under-test to be inserted into the EPQ machinery before starting an EPQ test query. That isn't sufficient to fix EPQ's general bogosity in the face of plans that return multiple rows per test row, though. Since this patch is mostly about getting some plan node infrastructure in place and not about fixing ten-year-old bugs, I will leave EPQ improvements for another day. Another behavioral change that we could now think about is doing FOR UPDATE before LIMIT, but that too seems like it should be treated as a followon patch.
* Split the processing of INSERT/UPDATE/DELETE operations out of execMain.c.Tom Lane2009-10-10
| | | | | | | | | | They are now handled by a new plan node type called ModifyTable, which is placed at the top of the plan tree. In itself this change doesn't do much, except perhaps make the handling of RETURNING lists and inherited UPDATEs a tad less klugy. But it is necessary preparation for the intended extension of allowing RETURNING queries inside WITH. Marko Tiikkaja
* Remove very ancient tuple-counting infrastructure (IncrRetrieved() andTom Lane2009-10-08
| | | | | | | | | friends). This code has all been ifdef'd out for many years, and doesn't seem to have any prospect of becoming any more useful in the future. EXPLAIN ANALYZE is what people use in practice, and I think if we did want process-wide counters we'd be more likely to put in dtrace events for that than try to resurrect this code. Get rid of it so as to have one less detail to worry about while refactoring execMain.c.
* Create an ALTER DEFAULT PRIVILEGES command, which allows users to adjustTom Lane2009-10-05
| | | | | | | | | | | the privileges that will be applied to subsequently-created objects. Such adjustments are always per owning role, and can be restricted to objects created in particular schemas too. A notable benefit is that users can override the traditional default privilege settings, eg, the PUBLIC EXECUTE privilege traditionally granted by default for functions. Petr Jelinek
* Ensure that a cursor has an immutable snapshot throughout its lifespan.Alvaro Herrera2009-10-02
| | | | | | | | | The old coding was using a regular snapshot, referenced elsewhere, that was subject to having its command counter updated. Fix by creating a private copy of the snapshot exclusively for the cursor. Backpatch to 8.4, which is when the bug was introduced during the snapshot management rewrite.
* Remove no-longer-needed ExecCountSlots infrastructure.Tom Lane2009-09-27
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* Replace the array-style TupleTable data structure with a simple List ofTom Lane2009-09-27
| | | | | | | | | | | TupleTableSlot nodes. This eliminates the need to count in advance how many Slots will be needed, which seems more than worth the small increase in the amount of palloc traffic during executor startup. The ExecCountSlots infrastructure is now all dead code, but I'll remove it in a separate commit for clarity. Per a comment from Robert Haas.
* Extend the BKI infrastructure to allow system catalogs to be givenTom Lane2009-09-26
| | | | | | | | | | | | hand-assigned rowtype OIDs, even when they are not "bootstrapped" catalogs that have handmade type rows in pg_type.h. Give pg_database such an OID. Restore the availability of C macros for the rowtype OIDs of the bootstrapped catalogs. (These macros are now in the individual catalogs' .h files, though, not in pg_type.h.) This commit doesn't do anything especially useful by itself, but it's necessary infrastructure for reverting some ill-considered changes in relcache.c.
* Rewrite the planner's handling of materialized plan types so that there isTom Lane2009-09-12
| | | | | | | | | | | | | | | | an explicit model of rescan costs being different from first-time costs. The costing of Material nodes in particular now has some visible relationship to the actual runtime behavior, where before it was essentially fantasy. This also fixes up a couple of places where different materialized plan types were treated differently for no very good reason (probably just oversights). A couple of the regression tests are affected, because the planner now chooses to put the other relation on the inside of a nestloop-with-materialize. So far as I can see both changes are sane, and the planner is now more consistently following the expectation that it should prefer to materialize the smaller of two relations. Per a recent discussion with Robert Haas.
* Tweak ExecIndexEvalRuntimeKeys to forcibly detoast any toasted comparisonTom Lane2009-08-23
| | | | | | | | | | | | | | | | | | values before they get passed to the index access method. This avoids repeated detoastings that will otherwise ensue as the comparison value is examined by various index support functions. We have seen a couple of reports of cases where repeated detoastings result in an order-of-magnitude slowdown, so it seems worth adding a bit of extra logic to prevent this. I had previously proposed trying to avoid duplicate detoastings in general, but this fix takes care of what seems the most important case in practice with very little effort or risk. Back-patch to 8.4 so that the PostGIS folk won't have to wait a year to have this fix in a production release. (The issue exists further back, of course, but the code's diverged enough to make backpatching further a higher-risk action. Also it appears that the possible gains may be limited in prior releases because of different handling of lossy operators.)
* Improve plpgsql's ability to cope with rowtypes containing dropped columns,Tom Lane2009-08-06
| | | | | | | | | | | by supporting conversions in places that used to demand exact rowtype match. Since this issue is certain to come up elsewhere (in fact, already has, in ExecEvalConvertRowtype), factor out the support code into new core functions for tuple conversion. I chose to put these in a new source file since heaptuple.c is already overly long. Heavily revised version of a patch by Pavel Stehule.
* Support deferrable uniqueness constraints.Tom Lane2009-07-29
| | | | | | | | | | The current implementation fires an AFTER ROW trigger for each tuple that looks like it might be non-unique according to the index contents at the time of insertion. This works well as long as there aren't many conflicts, but won't scale to massive unique-key reassignments. Improving that case is a TODO item. Dean Rasheed